March 7
The Heavy One
Sun Position
The Sun is in Pisces, declination near +10.5°; Northern Hemisphere evenings are arriving noticeably later, and Southern Hemisphere mornings are arriving noticeably earlier.
Sky Highlight
No major annual event falls on this date. Canis Major is still well-placed in the southwestern evening sky, setting after midnight from mid-northern latitudes, a final good week to catch the winter dog before it drops into the twilight glow.
Deep Sky Object
M41, an open cluster in Canis Major, about 2,300 light-years away, just 4° south of Sirius; it contains about 100 stars and is bright enough to see with the naked eye under dark skies, one of the few Messier objects that requires no optical aid. Visible from both hemispheres.
Featured Star
Wezen (δ CMa) lies about 1,600 light-years away and is a yellow-white supergiant of spectral class F8Ia, radiating roughly 50,000 times the Sun's luminosity behind a second-magnitude face that gives little hint of its true power. It is so intrinsically luminous that only its vast distance restrains its apparent brightness.
Around This Date
- March 7, 2009NASA's Kepler Space Telescope launched, beginning the mission that would discover more than 2,600 confirmed exoplanets and fundamentally change estimates of how common planets are around other stars.
- March 7, 1792John Herschel was born; he would go on to produce foundational star catalogs of the southern sky, continuing the systematic survey work begun by his father William.
Wezen puts 50,000 suns into a single second-magnitude point, distance is the great equalizer of the night sky.